I have a theory that many guitar manufacturers leave good looking wood finishes for natural guitars, and those which have blemishes, or don't look as good, are painted, often black. Either won't really affect the sound of the particular guitar, but it means more guitars can be made and sold - in fact, some players prefer coloured guitars.
Could be that this one was on the edge, or someone considered it to be fine natural. It's not beyond anything to ask for discount if you really like the sound and the way it plays. Or leave it and buy a different one. That choice is yours - bear in mind when selling it on that the blemishes may also put off prospective purchasers. But as long as it has a nice ring sound when it's tapped, there's nothing to worry about sound-wise. Only complexion-wise.
The two smaller things next to the fretboard look completely harmless to me, but the long one below the bridge looks like it might be a crack, and that could be problematic since cracks along the wood grain have a tendency to grow over time, and even a small crack may cause really annoying buzzing sounds.
I think in this case it's still ok since it's far enough away from the bridge where most force is concentrated, but I'd definitely take a really close look at that one. Is the surface properly even there? Does it sound suspiciously different when you knock with your fingers right next to that spot?
If it is a crack, then you should definitely consider making this a case for a discount.
My thought is that, if you are worried about this now, the worry will never go away.
You ask if the blemishes will flatten. Does this mean that you can feel them as well as see them? That would be very unusual. The answer is no. These things don't go away of their own accord. An expert might be able to remove any unevenness but this could cost you as much as the guitar is worth to be done properly..
If you are like me then every time you pick the guitar up you will be aware of the blemishes and you will never be 100% happy about it. My personal recommendation would therefore be to wait. If you are not like me then it makes sense to be guided entirely by the sound. If you are new to guitar then do your best to get an experienced player to go along with you.